Several weeks ago I had the thermostat housing replaced.

Now I smell a coolant odor when I exit the cab, and there is enough of it misting somewhere that I am prompted to cough after a while in the cab. For the record, I am asthmatic and hyper-sensitive to chemical odors and residue.

I've looked all over and cannot spot a source but I have on two occasions found spotting on the pavement under the right control arms. I've had to add over a half gallon to it since the "repair."

It will be after Thanksgiving before I can get it back to the shop.

In the meanwhile is there a dye that I can pour into the system to perhaps create a stain that will be visible under an ultraviolet light?

96,000 and a few miles on the vehicle. Other mechanical stats in the signature.

Thanks in advance,
Rick

 

I don't know about a dye but the next time you spot any coolant on the ground, give the engine a good looking over including from underneath. I don't know if the 2010 uses the same kind of plastic heater control valve as my 1996. I've had to replace mine several times.

 

Take a look under hood at the valve that controls coolant flow through the heater core. There are many reports of the valve leaking at the point where the lever exits the valve body. Only cure is replacement or bypass using tubing.
If the old thermostat housing was replaced due to it leaking, you may have more pressure being developed in the cooling system that is making the next 'leaker' start to show up.
If the coolant drips or sprays onto a hot surface(engine, exhaust manifold, etc) it will vaporize and cause an odor. It will also make the leak harder to find.
The coolant should have a color that distinguishes it from motor oil, gasoline, windshield washer fluid, brake fluid, etc. Most are gold, green, or sort of reddish. Take a look in the degas bottle, where the coolant is added, to know the color.
You might also run your hands on the underside of all hoses, collecting fluid will congregate on the down side, and you may find your leak. Also check where the hose clamps compress the hose onto the fittings. Loose clamps can allow seepage. You can use a screwdriver to tighten the screw-type clamps. Spring clamps may be replaced if they lose their 'spring'.
tom

 

Heater cores are a common replacement item.

 

Thanks to all for the suggestions. I topped off the coolant yesterday and have made several errands and short trips totaling around 60 miles. Part of it was on secondary roads and other of it on 4-lanes and the interstate at 70 mph +. The engine got thoroughly hot.

Additionally, yesterday and today were our first cold mornings of the fall so I've run the heater.

It has not leaked again and I'm not seeing anything on the engine or underneath. I checked the oil just to be sure and there is no sign of moisture in the oil. The coolant does not show signs of oil.

The reservoir is down just a hair from the halfway mark which is not enough that I would worry about it if I had not had the earlier issue.

Also, steam builds pressure that can force a leak at places hot liquid would not pass through.

So now I'm wondering, "could there have been a bubble in the system that would account for the fluid I had to add?"

 

Buy or rent a cooling system pressure tester. It makes finding exactly where coolant leaks are coming from sooo easy. The shop should've pressure tested it before sending it out the door. Since you had to add half a gallon of coolant, that indicates a pretty serious leak. It would've never passed the pressure test with a leak like that.

 

Thanks. I'll look into that. And I have a couple of questions.

1. Should I check it hot, or cold?

2. Do you happen to know what psi I need to apply to check it?

 

You only check it cold, especially since you have to remove the radiator cap to hook up the tester, and you should NEVER open the cap when it's hot.

You pump it up to whatever pressure the cap is rated for. In your case it would be 16 psi.

 

I had drops very similar to you, near the right control arms. Took me a long time to find it, but in my case it turned out to be a very slow leak from the water pump. Seemed that it would only drip after everything cooled down and lost pressure.

 

Okay, I think it is squared away.

Long story made short the shop replaced an O-ring and so hopefully, the matter is resolved.

I am not seeing a leak and the coolant odor is less obvious, but my asthma is letting me know there is still a residue on the motor. I'm thinking a good under the hood cleaning can help.

So I do have one other question: "What do I need to know, or do, before I spray wash the engine?"

 

Avoid spraying directly on fluid reservoirs and dipsticks, and avoid the alternator, computer, and wiring connectors. Also spray only on a cold engine. Other than that, spray away!

 

Roger that. Thanks.

Your suggestion is basically what I did - cold engine, not much pressure, etc.

The one exception is that I first dosed the engine good with Awesome, a biodegradable degreaser found at places like Dollar General.

It seems to have cleansed the residue off of the engine as I'm no longer smelling coolant or being prompted to the aggravating asthmatic cough.

Thanks again!